For implementation of electrical modules or components used in the context of electrical or electronic assemblies or devices, circuit boards are equipped with electrical or electronic components. In this case the circuit boards serve for mechanical fixing and for electrical coupling of components disposed on a circuit board. The electrical connections are produced by means of conductive tracks, for example copper conductive tracks.
An epoxy-glass mixture is usually used as circuit board material. In this case a circuit board may be of multi-layer construction and may have a plurality of conductive track levels or layers. In this way it is possible that each conductive track level or layer is provided individually with electrically conductive tracks, so that the number of possible electrical connections between the components disposed on the circuit board can be increased.
A conductive track level or layer may have a recess or an opening that enables the production of an electrical connection between conductive tracks on different conductive track levels, for example in that the recess or the opening is coated with electrically conductive material or an electrically conductive material is disposed in the recess or the opening and is electrically connected to the conductive tracks which are to be connected.
European patent document EP 0 926 929 A1 describes a multilayer circuit board with a plurality of conductive track levels disposed one above the other and separated by insulating material layers. A core substrate, which adapts the thermal expansion properties of the multilayer circuit board to thermal expansion properties of a component disposed on the multilayer circuit board, is disposed between the external insulating material layers. The core substrate is made of molybdenum.